Android-使用ViewPager实现高仿launcher拖动效果（转）

ViewPager是实现左右两个屏幕平滑地切换的一个类

使用ViewPager首先需要引入android-support-v4.jar这个jar包。具体ViewPager的用法

首先是layout下面的main.xml

    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

            android:id="@+id/viewPager"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

            android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

                    android:id="@+id/viewGroup"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_marginBottom="30dp"
            android:gravity="center_horizontal"
            android:orientation="horizontal" >
       
   

接下来为每一个切换界面设置布局item1.xml

    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

            android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@drawable/guide01" >
   

其他的几个界面布局和这个一样 ，就是修改下背景图片，所以不再复述，

最后是核心代码：
import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.widget.ImageView;

public class MainActivity extends Activity {
ViewPager viewPager;
ArrayList list;
ViewGroup main, group;
ImageView imageView;
ImageView[] imageViews;

@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  this.requestWindowFeature(Window.FEATURE_NO_TITLE);
  LayoutInflater inflater = getLayoutInflater();
  list = new ArrayList();
  list.add(inflater.inflate(R.layout.item1, null));
  list.add(inflater.inflate(R.layout.item2, null));
  list.add(inflater.inflate(R.layout.item3, null));
  list.add(inflater.inflate(R.layout.item4, null));
  list.add(inflater.inflate(R.layout.item5, null));

  imageViews = new ImageView[list.size()];
  ViewGroup main = (ViewGroup) inflater.inflate(R.layout.main, null);
  // group是R.layou.main中的负责包裹小圆点的LinearLayout.
  ViewGroup group = (ViewGroup) main.findViewById(R.id.viewGroup);

  viewPager = (ViewPager) main.findViewById(R.id.viewPager);

  for (int i = 0; i < list.size(); i++) {
   imageView = new ImageView(MainActivity.this);
   imageView.setLayoutParams(new LayoutParams(10,10));
   imageView.setPadding(10, 0, 10, 0);
   imageViews[i] = imageView;
   if (i == 0) {
    // 默认进入程序后第一张图片被选中;
    imageViews[i].setBackgroundResource(R.drawable.guide_dot_white);
   } else {
    imageViews[i].setBackgroundResource(R.drawable.guide_dot_black);
   }
   group.addView(imageView);
  }

  setContentView(main);

  viewPager.setAdapter(new MyAdapter());
  viewPager.setOnPageChangeListener(new MyListener());
}

class MyAdapter extends PagerAdapter {

  @Override
  public int getCount() {
   return list.size();
  }

  @Override
  public boolean isViewFromObject(View arg0, Object arg1) {
   return arg0 == arg1;
  }

  @Override
  public int getItemPosition(Object object) {
   // TODO Auto-generated method stub
   return super.getItemPosition(object);
  }

  @Override
  public void destroyItem(View arg0, int arg1, Object arg2) {
   // TODO Auto-generated method stub
   ((ViewPager) arg0).removeView(list.get(arg1));
  }

  @Override
  public Object instantiateItem(View arg0, int arg1) {
   // TODO Auto-generated method stub
   ((ViewPager) arg0).addView(list.get(arg1));
   return list.get(arg1);
  }

  @Override
  public void restoreState(Parcelable arg0, ClassLoader arg1) {
   // TODO Auto-generated method stub

  }

  @Override
  public Parcelable saveState() {
   // TODO Auto-generated method stub
   return null;
  }

  @Override
  public void startUpdate(View arg0) {
   // TODO Auto-generated method stub

  }

  @Override
  public void finishUpdate(View arg0) {
   // TODO Auto-generated method stub

  }
}

class MyListener implements OnPageChangeListener {

  @Override
  public void onPageScrollStateChanged(int arg0) {
   // TODO Auto-generated method stub

  }

  @Override
  public void onPageScrolled(int arg0, float arg1, int arg2) {
   // TODO Auto-generated method stub

  }

  @Override
  public void onPageSelected(int arg0) {
   for (int i = 0; i < imageViews.length; i++) {
    imageViews[arg0]
      .setBackgroundResource(R.drawable.guide_dot_white);
    if (arg0 != i) {
     imageViews[i]
       .setBackgroundResource(R.drawable.guide_dot_black);
    }
   }

  }

}
}